• Journal of IKEEE
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• v.22 no.1
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• pp.149-155
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• 2018

In this paper, we used ET(Electrical Tomography) for earth resistivity image reconstruction of vertical multi layer underground model. The earth resistivity is analyzed generally as the parallel multi-layer model, however possibly there happens vertical layer model. Here to find the best electrode array in case of vertical layer underground model, Wenner, Schlumberger, and Dipole-dipole electrode arrays, which are well known electrode arrays used in ET, have been tested. And Gauss-Newton algorithm is used in ET inversion. RMS error analysis shows that Wenner electrode array is best in imaging.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.7
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• pp.37-45
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• 2007

Recently, there has been an increase of the use of ground system for lightning protection called deeply driven grounding electrode. In the case of deeply driven grounding electrode, the rod electrode is equipped perpendicularly and deeply, therefore, it has a benefit to have less restriction of place compared to mesh grid electrode. However, ground impedance is largely changed by the local earth resistivity, so it requires a detailed analysis of the ground structure when planning. The measurement of earth resistivity by existing Wenner's method has been widely used, however, this method can not find out a change in the local ground resistance and it shows the result outwardly to be difficult to estimate exact depth. Therefore, this study analyzed the ground structure as 2-D image using 96 channels measurement facility and tried to analyze change in the local ground resistance and depth of the ground in order to design a deeply driven electrode effectively for lightning protection. It used Wenner alpha method dipole-dipole method and Schlumberger method for 2-D image analysis of the ground resistivity ma based on, it the result was compared with the ground structure analyzed with the result using the CDEGS and Wenner 1-D method.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.464-475
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• 2009

Electrical resistivity can be used for porosity estimation. In order to improve previously developed ERCP(Electrical Resistivity Cone Probe), 4ERP(4 Electrical Resistivity Probe), which has Wenner array at the tip of probes, has been developed. In properties of current flow Wenner array measures electrical properties of undisturbed area during penetration and relatively correct measurements are guaranteed without polarization. Furthermore, Wenner array equation can estimate electrical resistivity without extra calibration. 4ERP is developed into 2 types, penetration and fixation. Penetration type has wedge-shaped tip. Considering disturbance minimization, fixed type has plane tip. Fixed type 4ERP in consolidation cell measure electrical resistivity increment along porosity decrease, and penetration type 4ERP measured resistivity profile along the depth in chamber. Applying Archie's law, porosity profile was estimated with electrical resistivity. The tests result suggests that 4ERP can be new site investigation equipment with little disturbance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.35-41
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• 2011

In order to design effectively the grounding system, it is very important to determine the optimum soil resistivity at the desired location of the connection to earth. This paper deals with the reasonable methods of measuring the soil resistivity where grounding electrodes are buried. The soil resistivity at three test sites with different resistivity of soil were measured as functions of the spacing between the test probes in the Wenner's four-point method and the length of test ground rod in the three-point method. In the case of the three-point method, the length of test ground rod of 2-10[m] in length was appropriate in two-layered soil structure. In the length range of 2-10[m], the results measured by the three-point method using the test ground rod with the length corresponding to the spacing between the test probes of the Wenner's four-point method are in good agreement with the data obtained from the Wenner's four-point method.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1781-1782
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• 2006

In this paper, a methodology has been proposed according to which, after carrying out a set of soil's resistivity measurements using Wenner Four-probe data, one can compute the parameters of the multilayer earth structure using a genetic algorithm(GA). The results provided by the GA constitute the indispensable data that can be used in circuital or field simulations of grounding systems. The methodology allows to proceed toward a very efficient simulation of the grounding system and an accurate calculation of potential on the ground's surface.

• Journal of the Korean Geophysical Society
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• v.6 no.3
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• pp.155-164
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• 2003

The validity and efficiency of the roll-along technique widely used in 2-D electrical resistivity survey are analyzed in case of the dipole-dipole and the Wenner-Schlumberger arrays by numerical modelling. The shallow anomalous resistivity bodies are successfully inverted both in the dipole-dipole and in the Wenner-Schlumberger arrays because the shallow data of pseudosection are not omitted by the roll-along technique. However, the deep anomalous resistivity bodies can not be well resolved due to the skip of observed data which is more significant in the Wenner-Schlumberger array having relatively poor horizontal coverage of obtaining data. Carrying out electrical survey adopting the dipole-dipole array, the skip of data is insignificant because it is unfeasible to expand the electrodes to the maximum electrode separation coefficient($n_max$) owing to low S/N ratio. In case of the Wenner-Schlumberger array, however, because it is generally feasible to expand the electrodes $n_max$ to the owing to high S/N ratio, it is highly possible that skip of data from the roll-along technique causes significant distortion of inversion results. Therefore, adopting the Wenner-Schlumberger array having deeper median depth(Edwards, 1977) than do the dipole-dipole array on condition of the same unit electrode spacing( ($a$) ) and $n_max$, it is recommended to determine $a$ based on not $n_max$but $n_prob$free from the skip of observing data and forward electrodes with keeping overlap interval 3/4 of the survey line length in order to reduce the distortion of resistivity structure and perform resistivity survey efficiently. These results are confirmed by numerical modelling.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.382-386
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• 2001

Presently, typical maximum probe spacing of soil resistivity survey(Wenners 4 pin method) is 20 m in case of 154 K substation grounding design of KEPCO. This paper examined the effects of maximum probe spacing of wenner method on the equivalent soil modeling and the accuracy of grounding resistance measurement by comparing the calculated FOP(Fall-of-Potential) curves of various soil models with the measured one at 154kV H substation. The comparison results showed that the inaccurate estimation of deep soil resistivity, which is caused from the short probe spacing of soil resistivity survey, can produce large errors on measurement of grounding resistance. In this paper a quantitative analysis of FOP at H substation has been presented.

• Economic and Environmental Geology
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• v.19 no.3
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• pp.193-197
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• 1986

A simple and fast solution is derived to evaluate the effects of time-domain electromagnetic coupling in induced polarization surveys on a uniform earth. The simplified solution gives an explicit statement of the dependence of time-domain electromagnetic coupling on the model parameters, and yields sufficiently accurate results for most situations encountered in practice. The co-linear dipole-dipole and Wenner arrays are used as examples in this paper, but th numerical solution can be applied to any electrode configuration.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2355-2357
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• 1999

Estimating equivalent soil model which represents an actual soil structure and its electrical characteristics, is extremely improtant for good substation grounding system design and analysis. Since the equivalent soil model is deduced based on the measured apparent soil resistivity - generally obtained from Wenner's 4-point method, reasonable and accurate measuring technique and procedure guarantee good grounding system design and analysis. The paper aims to show the importance of reasonable enough probe spacing by presenting the influence of soil modelling to estimation and measurement of grounding resistance of substation grounding grid.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1492-1493
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• 2006

Wenner 4-probe arrangement is used most widely by the method to measure soil resistivity and the measured data with the Wenner method are apparent resistivities of the soil. Therefore, the soil structure can be analyzed easily from the measured apparent resistivity, but the real soil resistivity is difficult to know correctly at a particular depth or at a specific location on earth surface. This paper introduces a method that can be used to decide the suitable burial depth and the electrode scale of a grounding rod effectively using soil structure analysis equipment based on the dipole-dipole method.